Cleaning, disinfecting and microbicidal compositions

ABSTRACT

A microbicidal disinfecting composition and a method of preparing the same include the use of an acidifying agent that comprises at least one of an alkali metal bisulfate, ammonium bisulfate, or a combination thereof. The composition has broad-spectrum microbicidal properties and does not demonstrate cloudiness or precipitation when prepared, diluted, or otherwise exposed to hard water.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.12/912,171 filed on Oct. 26, 2010, which claims the benefit of U.S.Provisional Application No. 61/279,726 filed Oct. 26, 2009. Thedisclosures of the above applications are incorporated herein byreference.

TECHNICAL FIELD

The technical field of this disclosure generally relates to microbicidaldisinfecting compositions and methods of their preparation.

BACKGROUND

Microbicidal disinfecting compositions that include one or moremicroorganism-destroying antimicrobial agents as an active ingredientare used in a robust array of industrial, personal, and agriculturalsettings. The lethal effect of many antimicrobial agents towardsmicroorganisms is generally enhanced at acidic pH levels. For thisreason, the pH of common antimicrobial agents is typically adjusteddownward by an acidifying agent in the preparation of a microbicidaldisinfecting composition. Anionic surfactants such as esters of alkyland aryl sulfates and sulfonates, for example, are often combined withmineral acids and/or organic acids to achieve a level of acidityconducive to acceptable microbicidal activity. Mineral acids such aphosphoric acid, sulfuric acid, and hydrochloric acid, for example, areoften used to adjust the pH of alkyl and aryl sulfonated esters to formliquid microbicidal disinfecting compositions. Organic acids such ascitric acid and lactic acid, for example, are often used to adjust thepH of alkyl and aryl sulfated or sulfonated esters and to form powder orliquid microbicidal disinfecting compositions.

A microbicidal disinfecting composition prepared with mineral and/ororganic acids as the acidifying agent, however, has a tendency becomecloudy and show precipitate formation in hard water. This problem isoften combated by the addition of chemicals to prevent cloudiness andprecipitate formation—likely by decreasing the critical micelleconcentration. But the inclusion of additional chemicals into themicrobicidal disinfecting composition limits the extent to which theantimicrobial agent may be concentrated. The reliance on organic acidacidifying agents may further impact this physical constraint. Theseacids are typically weak acids and, as such, require larger quantitiesto achieve the desired acidic pH level when compared to mineral acids.

The use of organic acids and/or mineral acids as the primary acidifyingagent in the preparation of a microbicidal disinfecting composition cancomplicate handling, storage, and transportation concerns. The limitsimposed on the extent of antimicrobial agent concentration by theseacidifying agents and, as needed, additional chemicals to alleviateturbidity, can impact storage and transportation efficiencies. Certainmineral acids are also corrosive and may require special handling anddisposal procedures.

SUMMARY

An acidifying agent that includes at least one of an alkali metalbisulfate or ammonium bisulfate, both of which exhibit high aqueoussolubility, may be used to form a microbicidal disinfecting composition.These bisulfates help form an economical, generally non-hazardous, andstable microbicidal disinfecting composition for use in the foodprocessing, healthcare, personal care, and agricultural industries, toname but a few. The microbicidal disinfecting composition may beprepared in the form of a powder, a liquid solution, a gel, a foam, afog, a mist or as on a wipe.

A low concentration of the acidifying agent can provide the desiredacidity for a wide variety of antimicrobial agents without inducingcloudiness or precipitation when exposed to hard water. Thisdual-functionality of the acidifying agent may provide a number ofeconomic and product-application advantages. The use of an alkali metalbisulfate and/or ammonium bisulfate as all or part of the acidifyingagent, for example, allows for more concentrated microbicidaldisinfecting compositions to be prepared. The presence of additionalchemicals to inhibit cloudiness and precipitation may not be needed dueto the hard water tolerance of the alkali metal bisulfate and ammoniumbisulfate. The ability to achieve high antimicrobial agentconcentrations can reduce storage and transportation costs. As anotherexample, the hazards associated with handling, storing, and transportingmicrobicidal disinfecting compositions—both concentrated andready-for-use—made with corrosive mineral acids can be avoided. Alkalimetal bisulfates and ammonium bisulfate also cost less than organic acidand some mineral acid acidifying agents. This cost difference inconjunction with the low concentration effectiveness of the acidifyingagent may translate into raw material and/or production savings.

The acidifying agent may, in one embodiment, comprise at least one ofsodium bisulfate, potassium bisulfate, ammonium bisulfate, orcombinations thereof. Each of these bisulfates is available in foodgrade and technical grade. A food grade quality may be used when themicrobicidal disinfecting composition is meant to disinfect food contactsurfaces, or be included in an animal or public health product. Atechnical grade quality may be used for other appropriate purposes. Theacidifying agent may be employed with a number of antimicrobial agentsincluding anionic, cationic, and nonionic surfactants. A small samplingof exemplary antimicrobial agents include sodium dodecyl sulfate, sodiumdioctyl sulfosuccinate, sodium decyl lactylate, sodium dodecyl benzenesulfonate, and a quaternary ammonium compound. Other agents may also bepresent in the microbicidal disinfecting composition including afungicidal agent, a preservative, a flavoring agent, a coloring agent, afreeze-thaw modifying agent, or a sequestering agent. The addition of afungicidal agent, such as a copper or zinc salt, can afford themicrobicidal disinfecting composition with antifungal and algicidalcharacteristics.

Other exemplary and more detailed embodiments of the invention willbecome apparent from the detailed description that follows.

DETAILED DESCRIPTION

A microbicidal disinfecting composition may include an antimicrobialagent and an acidifying agent. The acidifying agent may include at leastone of an alkali metal bisulfate or ammonium bisulfate and may bepresent in an amount effective to provide the microbicidal disinfectingcomposition with an acidity conducive to the desired microbicidalactivity of the antimicrobial agent. The pH value of the microbicidaldisinfecting composition may range from very low up to 7.0 depending onthe current state of the composition or its intended use (highlyconcentrated for shipping/storage, less concentrated for end-useapplication, etc.). The amount of the acidifying agent needed to achievethis pH value target can vary quit considerably and may range from about0.1 wt. % to about 99.90 wt. %. The microbicidal disinfectingcomposition may also include, if desired, at least one of a fungicidalagent, a preservative, a flavoring agent, a coloring agent, afreeze-thaw modifying agent, or a sequestering agent.

The alkali metal bisulfate and/or ammonium bisulfate may, at lowconcentrations, provide the microbicidal disinfecting composition withthe acidity needed to support the effectiveness of the antimicrobialagent. The presence of hard water in the microbicidal disinfectingcomposition or the later addition of hard water will not promoteturbidity or precipitate formation. The use of an alkali metal bisulfateand/or ammonium bisulfate generally contributes to the formation of aclear solution when the microbicidal disinfecting composition is in aliquid aqueous state. The low concentration efficacy of these bisulfatesand their hard water tolerance can simplify, and reduce the costsassociated with, the preparation of the microbicidal disinfectingcomposition as compared to other similar compositions that use mineralacids and/or organic acids as the primary acidifying agent.

A method of preparing the microbicidal disinfecting composition mayinclude adding the acidifying agent to a liquid medium that includes anantimicrobial agent. The acidifying agent may be added in an amounteffective to considerably lower the pH value of the liquid medium toform an acidic concentrate. The acidic concentrate of the microbicidaldisinfecting composition may then be shipped or stored, either in liquidor powder form. The fact that additional chemicals do not have to beincluded in the acidic concentrate to prevent turbidity or precipitationwhen the microbicidal disinfecting composition is exposed to hard waterincreases the extent to which the antimicrobial agent may beconcentrated. Then, at some later time, the acidic concentrate may bediluted with water to form some intermediate microbial disinfectingcomposition or an end-use microbicidal disinfecting composition.

The alkali metal bisulfate may be sodium bisulfate, potassium bisulfate,or a combination of sodium bisulfate and potassium bisulfate. Each ofthese alkali metal bisulfates as well as ammonium bisulfate is availablein food grade and technical grade. The selection of which grade toselect for use in preparing the microbicidal disinfecting compositiondepends on the particular use for which the composition is intended, asunderstood by skilled artisans. The antimicrobial agent may be ananionic surfactant, a cationic surfactant, a nonionic surfactant, or anyother material that exhibits microbicidal activity in acidic conditions.The antimicrobial agent may be present in an amount ranging from about0.0001 wt. % to about 50 wt. %.

An anionic surfactant that may be employed as the antimicrobial agentmay comprise a C4-C18 acid or salt compound selected from the groupconsisting of: (1) an alkyl-carboxylate, isethionate, sulfate,sulfonate, sulfoacetate, sulfosuccinate, lactate, lactylate, phosphate,phosphonate, or mixtures thereof; (2) an alkenyl-carboxylate,isethionate, sulfate, sulfonate, sulfoacetate, sulfosuccinate, lactate,lactylate, phosphate, phosphonate, or mixtures thereof; (3) analkylbenzene-carboxylate, isethionate, sulfate, sulfonate, sulfoacetate,sulfosuccinate, lactate, lactylate, phosphate, phosphonate, or mixturesthereof; or (4) a naphthalene-carboxylate, isethionate, sulfate,sulfonate, sulfoacetate, sulfosuccinate, lactate, lactylate, phosphate,phosphonate, or mixtures thereof.

A more specific class of anionic surfactants that may be used include afree acid or a salt of (1) a C6-C18 alkyl sulfate, (2) a C6-C18 alkenylsulfate, (3) a C6-C18 alkyl ether sulfate, (4) a C6-C18 alkenyl ethersulfate, (5) a C8-C16 alkyl diphenyl ether disulfonate, (6) a C4-C18fatty acid isethionate, (7) a C6-C18 alkyl sulfonate, (8) a C6-C18alkenyl sulfonate, (9) a dialkyl sulfosuccinate in which the alkyl groupindependently contains from 6 to 18 carbon atoms, (10) a dialkenylsulfosuccinate in which the alkenyl group independently contains from 6to 18 carbon atoms, (11) a C6-C18 alkylbenzene sulfonate, (12) anaphthalene sulfonate, (13) an alkyl naphthalene sulfonate in which thealkyl group independently contains from 1 to 6 carbon atoms, (14) a mono(n-alkyl) acyl ester of a C2-C4 hydroxylated monocarboxylic acid inwhich the alkyl group independently contains from 6 to 18 carbon atoms,(15) a mono (n-alkenyl) acyl ester of a C2-C4 hydroxylatedmonocarboxylic acid in which the alkyl group independently contains from6 to 18 carbon atoms, (16) a mono (n-alkyl) acyl ester of a C2-C4hydroxylated dicarboxylic acid in which the alkyl group independentlycontains from 6 to 18 carbon atoms, (17) a mono (n-alkenyl) acyl esterof a C2-C4 hydroxylated dicarboxylic acid in which the alkenyl groupindependently contains from 6 to 18 carbon atoms, (18) a mono (n-alkyl)alkyl ester of a C2-C4 dicarboxylic acid in which the alkyl groupindependently contains from 6 to 18 carbon atoms, (19) a mono(n-alkenyl) alkyl ester of a C2-C4 dicarboxylic acid in which thealkenyl group independently contains from 6 to 18 carbon atoms, and (20)a C4-C18 fatty alcohol sulfoacetate.

Some preferred exemplary anionic surfactants that may be used as theantimicrobial agent include at least one of a sulfated alkyl ester, asulfated aryl ester, a sulfonated alkyl ester, or a sulfonated arylester. Some specific examples of such anionic surfactants are sodiumdodecyl sulfate, sodium dioctyl sulfosuccinate, sodium decyl lactylate,and sodium dodecyl benzene sulfonate.

A cationic surfactant that may be employed as the antimicrobial agentmay comprise, for example, a quaternary ammonium compound. Othercationic and nonionic surfactants known to skilled artisans may also beused as the antimicrobial agent.

The fungicidal agent may be any material that exhibits fungicidalactivity such as copper salts and zinc salts. Some specific fungicidalagents that may be included in the microbicidal disinfecting compositioninclude copper sulfate, cupric sulfate, and zinc sulfate. These metalsalts can provide the microbicidal disinfecting composition withantifungal and algicidal characteristics in the presence of theacidifying agent. The fungicidal agent may be present in an amountranging up to about 10 wt. %.

The preservative, flavoring agent, coloring agent, freeze-thaw modifyingagent, and sequestering agent may be any material known to skilledartisans. The preservative may, for example, be a free acid, salt, orester form of at least one of benzoic acid, sorbic acid, ascorbic acid,or erythorbic acid. The flavoring agent may be any known agent thatimparts a specific flavor (meat flavor, seafood flavor, fruity flavor,herbal flavor, etc.). These materials are generally commerciallyavailable. The coloring agent may be any coloring agent suitable for theintended use of the microbicidal disinfecting composition. Thefreeze-thaw agent may be any known organic or inorganic material thatcan be used to increase or decrease the freezing point of themicrobicidal disinfecting composition. Some specific examples offreeze-thaw agents include an alcohol, an inorganic salt, and urea. Thesequestering agent may be any material that binds to metal or toxiccompounds. Specific examples of suitable sequestering agents include,for example, sodium acid pyrophosphate, citric acid, isopropyl citrate,and calcium diacetate. Each of the preservative, flavoring agent,coloring agent, freeze-thaw modifying agent, and sequestering agent maybe included in the microbicidal disinfecting composition in an amountthat independently ranges from about 0.0001 wt. % to about 10 wt. %.

EXAMPLES

The Examples in Table 1 detail the preparation of several exemplarymicrobicidal disinfecting compositions. An anionic surfactant was usedas the antimicrobial agent and sodium bisulfate was used as theacidifying agent. The compositions were diluted with water fordetermining their microbicidal efficacy.

Example 1 Composition A

Ingredients % w/w Sodium dodecylbenzene sulfonate 33.33% Sodiumbisulfate 66.67% Total Wt 100.00% pH of 0.1% 2.54

Example 2 Composition B

Ingredients % w/w Sodium dodecylbenzene sulfonate 26.67% Citric acid20.00% Benzoic acid 13.33% Sodium bisulfate 40.00% Total Wt 100.00% pHof 0.1% 2.54

Example 3 Composition C

Ingredients % w/w Sodium dodecylbenzene sulfonate 13.33% Sodiumbisulfate 20.00% Lactic acid 33.33% Water 33.33% Total Wt 100.00% pH of0.2% 2.54

Example 4 Composition D

Ingredients % w/w Copper sulfate 10.00% Sodium bisulfate 90.00% Total Wt100.00% pH of 0.1% 2.54

Example 5 Composition E

Ingredients % w/w Copper sulfate 0.98% Sodium dodecylbenzene sulfonate2.44% Sodium bisulfate 96.59% Total Wt 100.00% pH of 0.1% 2.54

The microbicidal efficacy of the microbicidal disinfecting compositionsof Examples 1-3 (compositions A-C) were evaluated with 50 ppm ofhypochlorite as a control against Staphylococcus aureus and Escherichiacoli by the modified detergent and germicidal sanitizer test of theA.O.A.C. (Lopes, 1986). The results are shown in Table 1.

TABLE 1 Sanitizing % Kill Composition % w/v Staph. aureus E. coliExample 1 0.10 >99.999 >99.999 Example 2 0.10 >99.999 >99.999 Example 30.20 >99.999 >99.999 Hypochlorite 50 ppm >99.999 >99.999 Control

The microbicidal efficacy of the microbicidal disinfecting compositionof Example 1 (composition A) was further tested and proven effectiveagainst Salmonella on contaminated tomatoes. WhenSalmonella-contaminated tomatoes were treated with 0.1% solution ofcomposition A, the viable bacterial population was reduced by by 2.31log₁₀ CFU as compared with 2.11 log₁₀ CFU with 150 ppm of hypochlorite.

What is claimed is:
 1. A microbicidal disinfecting composition,consisting of: an antimicrobial agent in an amount ranging from about0.0001 wt. % to about 50 wt. %, based on the total composition weight,wherein the antimicrobial agent is selected from the group consisting ofan anionic surfactant, a nonionic surfactant, and combinations thereof;a fungicidal agent present in a positive amount of up to about 10 wt. %,based on the total composition weight, the fungicidal agent beingselected from the group consisting of a copper salt, a zinc salt, and acombination thereof; an acidifying agent that consists of an amount ofan alkali metal bisulfate effective to provide the microbicidaldisinfecting composition with a pH value of 7.0 or below; andoptionally, including one or more of water, a preservative, a flavoringagent, a coloring agent, a freeze thaw modifying agent, lactic acid, asequestering agent, or a combination thereof; wherein said preservativewhen present is selected from the group consisting of a free acid, asalt or an ester form of benzoic acid, sorbic acid, ascorbic acid, anderythorbic acid.
 2. The microbicidal disinfecting composition of claim1, wherein the antimicrobial agent comprises at least one of a sulfatedalkyl ester, a sulfated aryl ester, a sulfonated alkyl ester, or asulfonated aryl ester, and wherein the fungicidal agent comprises atleast one of copper sulfate, zinc sulfate, or combinations thereof. 3.The microbicidal disinfecting composition of claim 2, wherein theantimicrobial agent comprises at least one of sodium dodecyl sulfate,sodium dioctyl sulfosuccinate, sodium decyl lactylate, sodium dodecylsulfonate, or combinations thereof.
 4. The microbicidal disinfectingcomposition of claim of claim 1, wherein the acidifying agent consistsof an amount of sodium bisulfate, potassium bisulfate, or combinationsthereof.
 5. A microbicidal disinfecting composition, consisting of: ananionic surfactant having antimicrobial activity, the anionic surfactantbeing present in an amount that ranges from about 0.0001 wt. % to about50 wt. % of the microbial disinfecting composition; an amount of sodiumbisulfate, potassium bisulfate, ammonium bisulfate, or combinationsthereof, effective to provide the microbicidal disinfecting compositionwith a pH of 7.0 or less; lactic acid; and optionally, one or more ofwater, an anti-microbial nonionic surfactant, a fungicidal agent, apreservative, a flavoring agent, a coloring agent, a freeze thawmodifying agent, a sequestering agent, or combinations thereof; whereinsaid preservative when present is selected from the group consisting ofa free acid, a salt or an ester form of benzoic acid, sorbic acid,ascorbic acid, and erythorbic acid.
 6. The microbicidal disinfectingcomposition of claim 5, wherein the anionic surfactant comprises analkylbenzene sulfonate.
 7. The microbicidal disinfecting composition ofclaim 5, wherein the anionic surfactant comprises sodium dodecyl benzenesulfonate.
 8. The microbicidal disinfecting composition of claim 5,wherein said fungicidal agent is selected from the group consisting of acopper salt, a zinc salt, and a combination thereof, the fungicidalagent being present in an amount up to about 10 wt. % of the microbialdisinfecting composition.
 9. A microbicidal disinfecting composition,consisting of: at least one microbicidal alkylbenzene sulfonate; lacticacid; a second acidifying agent that consists of an amount of an alkalimetal bisulfate, ammonium bisulfate, or combinations thereof, that iseffective to provide the microbicidal disinfecting composition with a pHof 7.0 or less; and optionally, including one or more of water, anonionic surfactant, a fungicidal agent, a preservative, a flavoringagent, a coloring agent, a freeze thaw modifying agent, a sequesteringagent, or a combination thereof; wherein said preservative when presentis selected from the group consisting of a free acid, a salt or an esterform of benzoic acid, sorbic acid, ascorbic acid, and erythorbic acid.10. The microbicidal disinfecting composition of claim 9, wherein thealkylbenzene sulfonate comprises sodium dodecyl benzene sulfonate. 11.The microbicidal disinfecting composition of claim of claim 9, whereinthe second acidifying agent consists of sodium bisulfate, potassiumbisulfate, ammonium bisulfate, or combinations thereof.